@calculusxy

Buffy just put some money into a CD that pays 10.1% interest, compounded monthly. According to the rule of 72, in approximately how many years will she have 4 times the amount of money that she has now?

A. 7.1 years
B. 14.3 years
C. 28.5 years
D. 21.4 years

Question

@calculusxy 

Buffy just put some money into a CD that pays 10.1% interest, compounded monthly. According to the rule of 72, in approximately how many years will she have 4 times the amount of money that she has now?

 		A.	7.1 years
 		B.	14.3 years
 		C.	28.5 years
 		D.	21.4 years

calculusxy · Answer

What do have to do is divide 72 by 10.1% (since that is the interest rate). So then the quotient would then be 7.12. Since it is asking for four times the amount, you will have to multiply 7.12 with 4. The product will then be 28.48. Also this is asking for an estimate, so that will then end up to be 28.5 years.

calculusxy · Answer

Also meaning option C.

anonymous · Answer

oo ok because i was doing what you told me in the last question and i had got 7.12 but i didnt know if it was right